class_docstr: Samples elements from [start, start+length) sequentially.
  
  Parameters
  ----------
  length : int
      Length of the sequence.
  start : int, default is 0
      The start of the sequence index.
code: def __len__(self):
      return self._length
  
imports: import numpy
label_desc: Use image node_id 3 for calling the SequentialSampler obj's underlying member method code with example usage: obj.__len__() and returns: self